Self‐Powered Filterless Narrowband UV Photodetection Triggered by Asymmetric Charge Carrier Generation in a Wide‐Bandgap Halide Perovskite Ferroelectric

Abstract Narrowband photodetection with selective light detection in ultraviolet (UV) range is particularly pronounced in specialized applications such as targeted wavelength imaging and UV‐phototherapy. In contrast to conventional strategies, ferroelectric materials with pronounced bulk photovoltaic effect (BPVE) provide a novel asymmetric carrier generation concept for achieving filterless spectrally selective photodetection. Herein, for the first time, the realization of self‐powered filterless narrowband UV photodetection is demonstrated in bulk single crystals of a newly developed halide perovskite ferroelectric, 2FEA 2 EA 2 Pb 2 Cl 10 (2FEEPC), which exhibits a wide bandgap of 3.36 eV and a remarkable spontaneous polarization (≈3.5 µC cm −2 ). Benefiting from the strongly distorted inorganic framework with asymmetric delocalized electronic states, 2FEEPC demonstrates a highly wavelength‐dependent BPVE along the polar direction, showing a high narrowband detecting performance with a response peak at UV wavelength of 355 nm and a full‐width‐at‐half‐maximum (FWHM) of ≈15 nm. More interestingly, the ferro‐pyro‐phototronic effect of 2FEEPC endows a colossal gain of up to 600% for photopyroelectric current. This work presents an unprecedented approach to achieve self‐powered filterless narrowband photodetection, thereby shedding light on the development of photosensitive ferroelectrics for spectrally photoelectric applications.